There are now many types of electrical connectors for use in hostile environments. One category includes connectors intended for subsea mating and demating. And as a sub-category of these, there are connectors that are fluid-filled and pressure-balanced. The present invention, although not intended specifically for subsea use, falls within the scope of connectors of the last type.
One such connector is described by Buck, U.S. Pat. No. 3,508,188, wherein the connector receptacle sockets are housed in a fluid-filled chamber. In its simplest form the chamber has a sealed opening through which a male probe enters, said opening sealing against the shaft of the male probe in the mated condition. In the unmated condition, the opening seals against the elongate section of a piston contained within the receptacle socket assembly, and resiliently biased outwardly so as to follow the male probe into the opening as the probe is withdrawn. The opening is always sealed, therefore, either by being filled with the piston or with the male probe.
There are now many other subsea connector designs of the general sort proposed by Buck in the aforementioned patent, some of which are described by Briggs, U.S. Pat. No. 3,729,699; Butler, U.S. Pat. No. 4,142,770; Alcock, U.S. Pat. No. 4,795,359; Cairns, U.S. Pat. No. 4,948,337; Wilson, U.S. Pat. No. 4,039,242, and others.
The intention of these sealed fluid-filled connectors is to protect the electrical junctions from the outside environment by enclosing them within a chamber of benign non-conductive mobile dielectric substance such as oil, gel or grease (hereinafter referred to simply as oil or fluid), from which seawater is excluded. And such connectors do protect the junctions from the environment very well. There is a useful byproduct of this construction; these connectors are also spark-proof. If designed properly, they can be mated and demated with the receptacle sockets electrically energized. As the tip of the male probe approaches the energized socket, some arcing does take place, as it does any time a switch is thrown in an energized circuit But this arcing is contained within the oil-filled chamber and is partially suppressed by the oil. As a result, these connectors could be used in volatile atmospheres without danger of spark-induced explosions.
All of the aforementioned connectors are relatively large, being designed for the most part to be used in subsea systems where size is not a driving factor. The most reliable ones employ internal walls with elastomeric elements to define separate fluid-filled compartments around each circuit for redundant environmental protection. And they employ a relatively thick dielectric sleeve around the shank of each plug probe for the same reason. These elements contribute to the overall size.
There are demands for small, high circuit-density hostile-environment connectors which the above mentioned products cannot meet because of their size. These applications are not only in modern underwater sensor and control systems, but in medical, mining, petrochemical processing and other fields where harsh or explosive environments are encountered.
A goal of the present invention, therefore, is to provide a connector of the general sort just described, with redundant environmental and electrical barriers, but which is small enough so that it can be employed in a wide range of uses including spark-proof explosive-environment applications.
The invention laid out in the description to follow advances fluid-filled connector technology by substantially reducing the size of such connectors, leading to the possibility of packing a relatively large number of circuits in a confined space, while at the same time enhancing the isolation of the circuitry from the outside environment. It provides a pin and socket connector with redundant electrical and environmental protective barriers. In addition, the present invention provides an electrical connector with improved plug-probe and receptacle seal designs that contribute to miniaturization.